On worst case performance of collision avoidance systems

Author(s):  
Jonas Nilsson ◽  
Anders C.E. Odblom
2013 ◽  
Vol 325-326 ◽  
pp. 1071-1075
Author(s):  
Viera Poppeová ◽  
Juraj Uríček ◽  
Vladimír Bulej ◽  
Peter Havlas

This paper deals with the solving of collision detection in area of robotics. Collisions in robotics can cause damaging of robotic device, manipulated objects or in the worst case also the death of human. This is the reason why collision detection and collision avoidance is very important task and nowadays also the modern research is focused on finding of appropriate solving methods and tools. In the paper is described the theoretical introduction, practical solution and also real application.


2021 ◽  
Vol 5 (4) ◽  
pp. 1-26
Author(s):  
Alëna Rodionova ◽  
Yash Vardhan Pant ◽  
Connor Kurtz ◽  
Kuk Jang ◽  
Houssam Abbas ◽  
...  

Urban Air Mobility, the scenario where hundreds of manned and Unmanned Aircraft Systems (UASs) carry out a wide variety of missions (e.g., moving humans and goods within the city), is gaining acceptance as a transportation solution of the future. One of the key requirements for this to happen is safely managing the air traffic in these urban airspaces. Due to the expected density of the airspace, this requires fast autonomous solutions that can be deployed online. We propose Learning-‘N-Flying (LNF), a multi-UAS Collision Avoidance (CA) framework. It is decentralized, works on the fly, and allows autonomous Unmanned Aircraft System (UAS)s managed by different operators to safely carry out complex missions, represented using Signal Temporal Logic, in a shared airspace. We initially formulate the problem of predictive collision avoidance for two UASs as a mixed-integer linear program, and show that it is intractable to solve online. Instead, we first develop Learning-to-Fly (L2F) by combining (1) learning-based decision-making and (2) decentralized convex optimization-based control. LNF extends L2F to cases where there are more than two UASs on a collision path. Through extensive simulations, we show that our method can run online (computation time in the order of milliseconds) and under certain assumptions has failure rates of less than 1% in the worst case, improving to near 0% in more relaxed operations. We show the applicability of our scheme to a wide variety of settings through multiple case studies.


2016 ◽  
Vol 65 (4) ◽  
pp. 1899-1911 ◽  
Author(s):  
Jonas Nilsson ◽  
Anders C. E. Odblom ◽  
Jonas Fredriksson

Author(s):  
J.D. Geller ◽  
C.R. Herrington

The minimum magnification for which an image can be acquired is determined by the design and implementation of the electron optical column and the scanning and display electronics. It is also a function of the working distance and, possibly, the accelerating voltage. For secondary and backscattered electron images there are usually no other limiting factors. However, for x-ray maps there are further considerations. The energy-dispersive x-ray spectrometers (EDS) have a much larger solid angle of detection that for WDS. They also do not suffer from Bragg’s Law focusing effects which limit the angular range and focusing distance from the diffracting crystal. In practical terms EDS maps can be acquired at the lowest magnification of the SEM, assuming the collimator does not cutoff the x-ray signal. For WDS the focusing properties of the crystal limits the angular range of acceptance of the incident x-radiation. The range is dependent upon the 2d spacing of the crystal, with the acceptance angle increasing with 2d spacing. The natural line width of the x-ray also plays a role. For the metal layered crystals used to diffract soft x-rays, such as Be - O, the minimum magnification is approximately 100X. In the worst case, for the LEF crystal which diffracts Ti - Zn, ˜1000X is the minimum.


2008 ◽  
Author(s):  
Sonia Savelli ◽  
Susan Joslyn ◽  
Limor Nadav-Greenberg ◽  
Queena Chen

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